The Big Brother 7 star was one the former housemates linked to the show, which starts tomorrow night on Channel 4.
Horgan-Wallace, who was the top finishing girl in the seventh series, was expected to join a selection of other former favourites in the final two-week stint of the reality show.
She is rumoured to have turned down a £10,000 offer to return to the house because she is too busy working on spoof film Anuvahood. The project, which is scheduled for a 2011 release, currently has names such as Jamie Winstone, Ashley Walters and Adam Deacon attached.
In a statement, the glamour model, actress and author said: "Whilst Big Brother was an amazing experience and helped open a lot of doors for me, I feel that I am on to the next chapter of my life and am excited to be part of this film with an amazing cast."
Horgan-Wallace's post-Big Brother career has included launching her own clothing range and releasing her autobiography Surviving Guns, Gangs and Glamour last year.